Printed wiring boards are in common use in the electronics and telecommunications and other industries for creating conductive paths on interconnector devices. These conductive paths may be formed on one or both sides of a nonconductive substrate or one side of multiple substrates laminated together. It is generally required when employing double sided or multilayered printed wiring boards that through-holes be provided so as to interconnect conductive paths and interconnect devices between sides of the printed wiring boards. It is common to use as a starting material for the printed wiring board, a substrate having a blanket metal coating formed or laminated thereover and then providing the through-holes by drilling through the substrate in predetermined areas and subsequently plating the holes formed by drilling. Currently, metallization of these through-holes is accomplished by wet chemical processing including electroless plating techniques. Since the cost of vacuum metallization has been getting lower as large scale vacuum equipment becomes more available and reliable, while the costs of the alternative chemicals involved in wet chemical processing continue to rise, it would be desirable to replace the wet chemical techniques used for through-hole plating with more economical and more environmentally desirable dry metallization techniques such as vacuum metallization. Still another reason for reducing chemical processing wherever possible is the reduction of toxic chemical waste generated in chemical processing techniques. While it is not possible to totally eliminate wet chemical tecniques when using what is known in the art as subtractive technology for forming printed circuit boards employing metal laminated panels as a starting material, at least the steps of electroless deposition can be eliminated by substituting vacuum metallization for the electroless metallization of through-holes. While the purpose of the metallization is to cover the through-holes with a conductive metal deposit, it is necessary to overlap the through-hole metallization with the metal cladding on the surface of the board. Furthermore, the vacuum deposited layer must adhere well to both the through-hole and the metal cladding to prevent delamination. In attempting to make the substitution from electroless plating to vacuum metallization, however, it was discovered that the vacuum deposited copper had insufficient adhesion to the originally laminated copper foil such that the final circuits often exhibited layer-plating or interfacial delamination failure of the bond between the vacuum metallized layer and the original laminate or between a later electroplated copper layer on the conductor paths of the circuits and the original laminated copper. Industry standards for adhesion require at least a five pound per inch peel strength with a 90.degree. peel and preferably one seeks at least an 8 pound per inch peel strength. Until the discovery of the cause of the lack of adhesion and the removal or solution of this cause, vacuum metallization of the through-holes could not be accomplished for practical commercial use.